docs: def _make_bridge_request_msg(self, channel, netfn, command):
          """This function generate message for bridge request. It is a
          part of ipmi payload.
          """
          head = bytearray((constants.IPMI_BMC_ADDRESS,
                            constants.netfn_codes['application'] << 2))
          check_sum = _checksum(*head)
          # NOTE(fengqian): according IPMI Figure 14-11, rqSWID is set to 81h
          boday = bytearray((0x81, self.seqlun, constants.IPMI_SEND_MESSAGE_CMD,
                             0x40 | channel))
          # NOTE(fengqian): Track request
          self._add_request_entry((constants.netfn_codes['application'] + 1,
                                   self.seqlun, constants.IPMI_SEND_MESSAGE_CMD))
          return head + bytearray((check_sum,)) + boday